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Mercury Outboard Parts
Shop OEM and aftermarket Mercury outboard parts for maintenance, repair, troubleshooting, and complete engine rebuild projects. Browse Mercury marine parts by system, including cooling, fuel delivery, electrical and ignition, internal engine components, lower unit parts, steering, trim, and routine service items.
Pro Marine USA carries Mercury outboard engine parts for a wide range of 2-stroke, FourStroke, EFI, Optimax, Pro XS, SeaPro, and Verado applications. Use your engine horsepower, model, serial number, or OEM part number whenever possible to confirm fitment before ordering.
Shop Mercury Outboard Parts by System
- Complete Powerheads
- Control Cables & Boxes
- Cooling System
- Cowlings & Components
- Electrical System
- Engine Oil
- Engine Rebuild Kits
- Fuel & Carburetion System
- Intake System
- Internal Engine Components
- Lower Unit Components
- Oiling System
- Paints
- Service & Oil Change Kits
- Service Manuals
- Steering Systems
- Throttle Components
- Transom & Midsection
- Trim System
- Wizard Performance Parts
Find the Correct Mercury Outboard Part
Mercury outboard parts can vary by horsepower, engine family, model year, and serial number range. If you are unsure which component fits your engine, use the OEM parts lookup to locate the original Mercury part number from an engine diagram.
Once you have the OEM part number, search Pro Marine to find available genuine Mercury and aftermarket replacement options.
Use Our OEM Parts Lookup »Common Mercury Outboard Engine Families
Pro Marine supports many Mercury outboard applications across a wide horsepower range. Always confirm the engine serial number and model information before ordering parts.
- Portable and Midrange: Mercury 2.5HP through 60HP 2-stroke and FourStroke applications
- FourStroke and EFI: common 75HP through 300HP Mercury EFI and FourStroke platforms
- Pro XS: performance-oriented Mercury Pro XS outboards across multiple engine families
- Optimax: direct-injected 2-stroke Mercury Optimax engines, commonly 75HP through 250HP
- Verado: supercharged and naturally aspirated Mercury Verado applications from 135HP through current high-horsepower platforms
- SeaPro: commercial-duty Mercury SeaPro outboards used in professional and high-hour applications
Common Mercury Outboard Repair Areas
- Overheating: inspect the water pump, impeller, thermostat, poppet valve, cooling passages, and related cooling components.
- Hard starting or rough running: inspect fuel pumps, filters, injectors or carburetors, spark plugs, coils, sensors, and intake components.
- No spark or intermittent ignition: check ignition coils, stators, switch boxes, trigger assemblies, sensors, grounds, and wiring.
- Low compression or power loss: inspect pistons, rings, cylinders, bearings, gaskets, reeds, and internal engine components.
- Lower unit noise or water intrusion: inspect seals, bearings, gears, shafts, bearing carriers, and gear lube condition.
- Trim or steering problems: inspect trim motors, pumps, hydraulic components, steering cylinders, hoses, and related rigging parts.
Why Buy Mercury Outboard Parts from Pro Marine USA?
- OEM Mercury and aftermarket replacement options for many common applications.
- Parts for maintenance, repair, engine rebuilding, lower units, electrical systems, fuel systems, steering, trim, and rigging.
- OEM diagram and part-number lookup tools to help identify the correct part before ordering.
- Dealer pricing available for qualified marine repair businesses and dealers.
- Large inventory of Mercury service parts and hard-to-find marine engine components.
- Fast weekday shipping on qualifying in-stock orders.
Frequently Asked Questions
How do I find the correct Mercury outboard part?
Use the engine horsepower, model, serial number, and year whenever available. Mercury frequently uses serial-number ranges to identify engine families, so the serial number is often the most reliable way to confirm fitment.
Can I search Mercury parts by OEM part number?
Yes. Enter the Mercury OEM part number into the Pro Marine site search to locate available OEM and aftermarket replacement options. If you do not know the part number, use the OEM parts lookup first.
Do Mercury outboard parts vary by serial number?
Yes. Many Mercury components change by serial-number range even within the same horsepower or model family. Always compare the serial range listed for the part with your engine before ordering.
Do you carry parts for Mercury Optimax and Verado engines?
Yes. Pro Marine carries parts for many Mercury Optimax, Verado, Pro XS, EFI, FourStroke, and SeaPro applications, including maintenance, fuel, electrical, cooling, internal engine, lower unit, steering, and rigging components.
Do you carry both OEM and aftermarket Mercury parts?
Yes. Pro Marine offers genuine Mercury parts along with aftermarket replacement parts for many common Mercury outboard maintenance, repair, and rebuild applications.
What Mercury outboard parts are commonly replaced during routine maintenance?
Common maintenance items include engine oil, oil filters, fuel filters, spark plugs, water pump kits, impellers, thermostats, gear lube, drain plug seals, anodes, and manufacturer-specific service kit components.
Fitment Tip: Mercury outboard parts often vary by serial-number range. Confirm your engine serial number and OEM part number whenever possible before ordering.
21020
37428A1
508708
55419A1
775499
77631A2
9-76134
812966A3
812966A7
812966A9
9-43330
Fits Select Mercury 25-70HP Gearcase Applications
Designed for Mercury and Mariner lower unit bearing carrier assemblies. The Mercury 21700 Bearing, also listed as 31-21700, is a needle / roller bearing used in the gearcase bearing carrier area to support the propeller shaft.
Compatibility
This bearing is used across many Mercury and Mariner small to midrange outboard gearcases. OEM where-used data shows applications across multiple 25-70HP gearcase families, including 2-stroke, 4-stroke, BigFoot, and Jet models.
Application Chart
| Brand | Engine Family | Horsepower | System | Component |
|---|---|---|---|---|
| Mercury / Mariner | Small 4-Stroke Outboards | 25-30 HP | Gearcase / Lower Unit | Bearing Carrier / Prop Shaft Bearing |
| Mercury / Mariner | 2-Cyl / 3-Cyl Outboards | 35-40 HP | Gearcase / Lower Unit | Bearing Carrier / Prop Shaft Bearing |
| Mercury / Mariner | 3-Cyl / 4-Cyl Outboards | 45-60 HP | Gearcase / Lower Unit | Bearing Carrier / Prop Shaft Bearing |
| Mercury / Mariner | BigFoot / 4-Stroke Models | 40-60 HP | Gearcase / Lower Unit | Bearing Carrier / Prop Shaft Bearing |
| Mercury / Mariner | 70HP 3-Cyl Outboards | 70 HP | Gearcase / Lower Unit | Bearing Carrier / Prop Shaft Bearing |
| Mercury / Mariner | Jet Models | 30-45 Jet | Gearcase / Jet Drive | Bearing Carrier / Prop Shaft Bearing |
Always confirm compatibility using your engine serial number, gearcase type, and existing part number before ordering.
Part Numbers & Cross References
| Reference Type | Part Number |
|---|---|
| Mercury OEM Part | 21700 |
| Mercury OEM Part | 31-21700 |
| Cross Reference # | 18-1095 |
| Cross Reference # | 93-263-12 |
| Cross Reference # | 11428 |
What This Part Is Used For
This bearing is used in the lower unit bearing carrier to support the propeller shaft. A properly functioning bearing helps maintain smooth prop shaft rotation and proper gearcase operation.
Bearings are commonly inspected or replaced during lower unit rebuilds, bearing carrier service, prop shaft repair, or when gearcase noise, vibration, or wear is found.
Frequently Asked Questions
What does Mercury 21700 fit?
This bearing fits select Mercury and Mariner small to midrange gearcases, commonly in the 25-70HP range. Always verify by serial number and gearcase diagram.
Where is this bearing used?
It is used in the lower unit bearing carrier area to support the propeller shaft.
Is 21700 the same as 31-21700?
Yes. Mercury commonly lists this bearing as 31-21700.
When should this bearing be replaced?
Replace it during lower unit rebuilds or when wear, noise, corrosion, or prop shaft bearing damage is found.
Dealer Discounts & Store Policies
Dealer / Marine Industry Discounts
Are you a marine dealer or technician? We offer dealer pricing for qualified businesses.
Shipping Policy
- Free shipping on orders over $100 (continental U.S.)
- Ships via UPS, USPS, and FedEx
- 5:30 PM EST daily cutoff
- Typical delivery 1–5 business days
30-Day Return Policy
- Returns within 30 days
- Items must be unused and in original packaging
- Return authorization is required before sending items back
Contact Us
Phone: 941-721-3000
Searchable Part Numbers
Part Number: 21700
Cross Reference #: 31-21700, 18-1095, 93-263-12, 11428
Common Search Terms: Mercury 21700 bearing, Mercury 31-21700 bearing, Mercury bearing carrier bearing, Mercury prop shaft bearing
855721T8
856156A2
856156T02
89492T
89495
17791A94
17791A95
17791A97
17791A98
17791R95
17791R97
17791R996
17791T97
822212T
8154331
856156A4
856156T02
856156T04